Psychologist Angela Duckworth studies the traits that allow us to stick to our goals — and she chose four great talks that explore other facets of how human beings behave.

These TED Talks will help you conjure up massive amounts of gratitude.

How to be happier at work? Start by focusing on happiness -- not, surprisingly, on work. We learned this fun fact from Shawn Achor's TED Talk. So we asked Achor to choose some more talks he loves, about making work and life a happier place.